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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../jquery.min.js"></script>
    <style>
        * {
            margin: 0;
            padding: 0;
            list-style: none;
            text-decoration: none;
        }

        .father>li {
            float: left;
            padding: 0 10px;
        }

        .father ul {
            display: none;
        }
    </style>
</head>

<body>
    <ul class="father">
        <li>
            <a href="#">微博</a>
            <ul>
                <li>私信</li>
                <li>评论</li>
                <li>@我</li>
            </ul>
        </li>
        <li>
            <a href="#">微博</a>
            <ul>
                <li>私信</li>
                <li>评论</li>
                <li>@我</li>
            </ul>
        </li>
        <li>
            <a href="#">微博</a>
            <ul>
                <li>私信</li>
                <li>评论</li>
                <li>@我</li>
            </ul>
        </li>
        <li>
            <a href="#">微博</a>
            <ul>
                <li>私信</li>
                <li>评论</li>
                <li>@我</li>
            </ul>
        </li>
    </ul>
</body>
<script>
    $(function () {
        $(".father>li").hover(function () {
            $(this).children("ul").stop().slideToggle(200);
        })
    })
</script>

</html>